There are hydraulic devices in which hydraulic oil is supplied from a single large-displacement pump to a torque converter, a steering device, and a multi-stage transmission for performing gear-shifting by selectively engaging and releasing a plurality of hydraulic clutches. An example of the hydraulic device according to the related art is shown in FIG. 10. In the hydraulic device, low-pressure high-flow hydraulic oil is needed in order to operate a torque converter 200, and high-pressure low-flow hydraulic oil is needed in order to operate a multi-stage transmission 100 and a steering device 300. In view of this, in this hydraulic device, a single large-displacement pump 500 outputs high-pressure high-flow hydraulic oil to a hydraulic oil line P10. At this time, the multi-stage transmission 100 and the steering device 300 are supplied with only a low flow rate of hydraulic oil at a high pressure. The torque converter 200 is supplied with a high flow rate of hydraulic oil that has undergone pressure relief through a pressure regulator 310 and whose pressure has been lowered. In other words, since an extremely small amount of oil is needed to operate the multi-stage transmission 100 and the steering device 300, a large portion of the hydraulic oil supplied from the pump 500 is supplied to the torque converter 200.
There are also hydraulic devices equipped with a pump designated for operating the multi-stage transmission, a pump designated for operating the torque converter, and a pump designated for operating the steering device (for example, see Japanese Laid-open Patent Application Publication No. 56-5224).